HELP NEEDED - CRF450 Pumping Oil Out Valve Cover Breather

[rikhek]

My 05 Honda CRF450 is putting a significant amount of oil out the valve cover breather. NOT a "normal" amount. Bad enough that it goes below sightglass after 2 hours run time. I'm certain it's coming out the vent. Bike runs fine.

Would appreciate someone letting me know what's wrong.

TIA

Rick

 

[Matt90GT]

Most likely blowby of the piston.

Time to do a leak down test of the motor.

 

[Spokes574]

to me that is one of two issues:
-Worn piston rings will do that! - this was in last month magazine Mx Action
-Over filling the oil, putting in too much oil
Spokes574

 

[rikhek]

To those interested the top end was worn causing excessive blowby. New top end and all is well.

Rick